Abstract: For the functional failure problem of aircraft door lock mechanism with joint clearances, a practical reliability and sensitivity method is studied based on interval model. The clearances caused by design, manufacture, installation, wear and other factors are characterized by interval model, and a co-simulation model for the reliability analysis of the door lock mechanism is established in ADAMS and Matlab software. The interval variable based non-probabilistic reliability index is introduced, and the sensitivity index for evaluating the influence of interval variables on mechanism reliability is proposed. The proposed non-probabilistic reliability and sensitivity method is applied to the study of aircraft door lock mechanism. The results show that the proposed method has lower requirements for engineering sample data, fewer assumptions and higher calculation efficiency to evaluate the reliability of the lock mechanism. At the same time, the sensitivity analysis can screen out the key positions that affect the functional reliability of the lock mechanism, thus providing guidance for the optimization design of the door lock mechanism.